Revolving-hook sewing-machine.



R. K. HOHMANN.

REVOLVING HOOK SEWING MACHINE.

APPLICATION FILED SEPT. 18, l9l2.

1 1 98,546. I Patented Sept. 19, 1916.

4 SHEETS-SHLET I.

R. K. HOHMANN.

Patented Sept. 19, 1916.

4 SHEETS-SHEET 2- f m T? 1 I kg m R K. HOHMANN.

REVOLVING HOOK SEWING MACHINE.

APPLICATION FILED SEPT. 18. 1912.

Patented Sept. 19, 1916.

4 SHEETS-SHEET 3 R. K. HOHMANN.

REVOLVING HOOK SEWING MACHINE.

APPLICATION FILED SEPT. I8. I912.

Patented Sept. 19, 1916. 4 SHEET-SHEET 4 RICHARD K. HOHMANN, OF SAN DIEGO, CALIFORNIA.

REVOLVING-HOOK SEWING-MACHINE.

Specification of Letters Patent.

Patented. Sept. 19, 1916.

Application filed September 18, 1912. Serial No. 721,040.

To all whom it may concern:

Be it known that I, RICHARD K. Horr- MANN, a citizen of the United States, residing at San Diego, county of San Diego, State of California, have invented certain new and useful Improvements in Revolving- Hook Sewing-Machines, of which the following is a specification.

This invention relates to sewing machines in which the loop of thread is carried around the lower bobbin or spool by means of a revolving hook.

It has particular reference to the structure of the revolving hook, the structure of the spool holding mechanism around which the hook works and the mechanism for retaining the spool holder against rotation as the loop passes around it.

The novel features of the invention will be apparent from the following description taken in connection with the drawings.

In the drawings: Figure 1 is a face view of a sewing machine embodying my invention. Fig. 2 is a bottom plan view. Fig. 3 is a front view of the head of the machine with the face plate removed. Fig.4 is a side view of the revolving hook mechanism including the spool holder. Fig. 5 is a vertical section of the structure shown in Fig. 4. Fig. 6 is a similar view with the spool holder removed. Fig. 7 is a perspective view of the spool holder. Fig. 8 is a side view of the frame which carries the spool holder and around which the hook rotates. Fig. 9 is a rear elevation of the rotary hook and operating mechanism.

As shown in these drawings my invention is applied to a sewing machine of a general type well known in the art and therefore in the present case it is not necessary to describe in detail many of the well known features which are shown.

The machine includes the metal table 1, which is adapted to fit on the ordinary wooden table and which carries the working parts of the machine. It includes the usual hollow upright member 2 carrying a hollow horizontal member supporting the head of the machine in which the needle bar 3 works vertically and in which the usual presser foot bar 4 is mounted. The head 5 is provided with the usual thread guides with the tension device 6 and the take-up arm 7 Below the top of the table and parallel therewith a rotary shaft 8 is mounted and it is of course to be turned in any well and forwardly.

known way. At its forward end at the point where the needle passesdown through the.

needle plate 9 the shaft 8 is provided with a circular head 10 which is in the shape of a rlng having its surface parallel to the shaft 8 and there is a peripheral flange 11 at the rear edge of this ring-like portion and these parts are corinected to the shaft 8 by a metal surface which flares outwardly In the particular form shown this metal connection consists of sheet metal bent into shape, holes 12 being cut therein for the purpose of reducing its weight, but it will be understood that the particular form of this construction is not essential. The ring-like part 10 and the flange 11 do, however, constitute part of my invention and the revolving hook ring 13 fits on the circular head 10 and is pushed back into place against the flange 11, being held there by suitable fastening means passing through the flange 11, such as the screws 14 The revolving ring 13 has on its edge the hook 15 for engaging the loop of thread and there is an interior inwardly projecting flange 16 at the forward edge of this ring, this flange cooperating with the forward edge of the circular head 10 to form an interior groove to receive the bearing rim of theframe 17 which carries the spool holder. This makes a construction which is not only eflicient and durable mechanically, but one which can be easily made and in which the parts can be assembled without trouble.

The frame 17 has a. pin 18 pivoted at 19 to its inner edge at the bottom so that this pin can lie within the plane of the bearing rim on the frame 17, or can be turned outward to the position shown in Fig. 6. A small spring 20 may be secured to the frame and bear on the rear face of the pin below the pivot so as to tend to hold it in operative position in the plane of the bearing rim. A cylindrical spool holder 21 is provided with a central hollow shaft 22 adapted to fit over the pin 18 and this holder may have on its bottom afiiange 23, fitting behind the pivot of the pin 1,8 and behind the lugs 24, to which that pin is pivoted so as to prevent the spool holder 21 from turning on the pin 18. This holder may furthermore have the projections 25 at its ends for the purpose of preventing its rotation. In the upper end of the hollow shaft 22 a pin 26 is mounted and it is supported by a spring 27 which .tends to force it outward. A bushing 28 is screwed into the upper end of the hollow shaft 22 around the pin 26 and that'pin is free to slide in this bushing, but is limited in its outward movement by an enlarged inner end which provides a shoulder or stop. This spring pressed pin 26 cooperates with a depression in the projection 29 on the inner face of'the frame 17 so as to yieldingly hold the spool holder and the pin 18 in operative position when it is turned to the position shown in Fig. 5.

It will of course be understood that a spool of thread is placed over the hollow shaft 2-2, and it will be seen that when the spool holder is placed on the pin 18, in the position shown in F ig. 6, it can be snapped into the position shown in Fig. 5 where it is ready for operation and in order to remove the spool it is only necessary to exert a slight pressure of the finger on the spool holder to make the spring retaining means yield and the parts turn out into the position shown in Fig. 6 where the spool can be removed.

It will be observed from the construction shown that the spool holder will contain either an ordinary spool of thread or a bobbin. This spool holder is of course provided with the necessary thread guiding slots and the tension plate 30.

Since the frame 17 carrying the spool holder rests loosely within the revolving hook ring 13 it is clear that some means must be provided for preventing the rotation of that frame as the loop of thread is passed around it and in Figs. 1, 2 and 9 I have shown such means. On the face of the frame 17 there are projections having therein radial slots 31, 32 and the rocking member 33 is mounted on a shaft 34 which is parallel to the shaft 8 and which is directly beneath it. This rocking member has at its ends inwardly projecting fingers 35, 36 adapted to enter the slots 31 and 32 and it will be clear that so long as one of these fingers is in one of the slots the frame 17 cannot rotate. This rocking member takes up little room and can be "easily and cheaply made.

The member 33 is given its oscillating movement to bring the fingers 35 and 36 alternately into operative position by the means shown most clearly in Fig. 9. This includes a cam 37 carried by the shaft 8 and a forked arm 38 secured to the rock shaft 34 at the rear of the revolving hook.

This forked arm 38 has the two arms 39,

40 which are parallel and which fit closely the sides of the cam 37 and it will be observed that the bearing faces of this arm are arranged at an angle to a line drawn through the shafts 8 and 34. By this arrangement it will be observed that as the shaft 8 turns the projecting portion of the cam 37 strikes the arm 39 near the pivot timing.

point on shaft 34, thus giving to it a quick motion and because of the short leverage given to the shaft-34 a large rocking movement compared to the size of the cam. When the projecting portion of the cam reaches the arm 40 it will because of the inclined relation of that arm give to it a greater rocking movement than that due merely to the size of the projection on the cam. This angular arrangement of the operating arm 38 not. only enables me to economize space, but it enables me to secure more easily and more effectively the quick rocking movement of the member 33 and by the shape of the cam to secure the proper It will of course be understood that the member 33 is rocked so as to permit the loop of thread to pass freely around the spool holder and the rocking movement is properly timed with reference to the rotation of the loop engaging hook so that the thread will pass freely. The two fingers 35 and 36 are arranged in the bottom part of the circular hook mechanism and this is found necessary in order to prevent inter ference and breaking the thread.

The mechanism for operating the clothfeeding device is also located at the rear of the revolving hook mechanism as shown in Fig. 9. As is well known it is necessary to give to the cloth-feeding member 41 having the rough upper surface below the presser foot 42 not only a horizontal, but a vertical movement so that it .will engage the cloth, move forward, then drop below the cloth plate and move back to the original position below the plate. As shown in the drawing this feeding arm 41 is secured to a part 43 which is pivoted at 44, but the pivot 44 can move back and forth because it is mounted on an arm 45 pivoted at its lower end at 46. The pivot shaft 44 has secured to it an arm 47 which projects over the shaft 8 and rests on the cam 48 on that shaft. The turning of the 'shaft 8 and the operation of the cam 48 therefore raises the arm 47 periodically and this results in raising the cloth-engaging member 41 so as to bring it up into the position shown in Fig. 1. A link arm 49 is also secured to the pivot shaft 44 and extends out toward the shaft 8, its rounded end being in line with the arm 50 which is pivoted at 51, and which has a roller 52 hearing against the face of the cam 53 on the shaft 8. The rotation of the cam 53 rocks the arm 50, thus moving the arm 49 longitudinally, rocking it together with the feeding device 41 and giving to that feeding device the necessary longitudinal motion to feed the cloth. The inner end of the arm 49 is supported by a link arm 53 pivotally connected to the end of an arm 54 secured to a rotatable shaft 55 and it will be seen therefore that by turn-- ing the shaft 55 the inner end of the arm 49 may be raised or lowered so as to bring it opposite .difi'erent portions of the rocking arm 50 and in this way the amount of ionitudinal movement given to the cloth feedmg device 41 can be regulated. When the arm 49 is brought down near the pivot point of arm 50 a short stitch will. be formed, where as when it is raised the stitch will be made longer.

Having thus described the invention what is claimed is:

1. A bobbin holder for rotary hook sewing machines comprising a frame having a peripheral bearing rim, a pin pivoted at one end to the inner edge of said rim, a spool holder having a hollow central shaft adapted to fit over said pin, and a sp ing pressed member in the end of said ho low shaft adapted to engage said rim at the side.

opposite the pivot of said pin to latch the parts in position.

2. A bobbin holder for rotary hook sewing machines comprising a frame having a peripheral bearing rim, a pin pivoted at one end to the inner edge of said rim, a spool holder comprising a casing open at one end and having a hollow central shaft open at the other end adapted to fit over" said pin, and spring pressed means in the hollow shaft of said holder for yieldingly engaging said rim when turned to operative position.

In testimony whereof I aflix my signature in presence of two witnesses.

RICHARD K. HOHMANN. Witnesses:

JOHN M. Corr, B. C. RUST. 

